1. Field of the Invention
The present invention relates generally to medical devices and methods for the treatment and/or management of epilepsy. More specifically, the invention relates to devices and methods for controlling the baroreflex system for the treatment and/or management of epilepsy.
An estimated 1% of the world's population suffers from epilepsy. Of these, approximately 30,000 patients each year suffer from medically intractable epilepsy, and alternative treatments have not yet been perfected. Only 15% of patients will benefit from presently existing cerebral surgery techniques. Vagal nerve stimulation (VNS) offers 20-61% seizure reduction (at 3-month or greater follow-up) according to most large studies, but is associated with undesirable side effects, such as hoarseness, coughing, dysautonomia, and, in right-sided VNS, cardiac side effects. Of the approximately 50% of patients whose seizures are not well controlled by VNS, as well as for those patients in whom VNS is difficult or contraindicated (e.g., due to prior scarring from radiation, cancer-related surgery, or the like), other therapeutic options are not currently available.
Vagal nerve stimulation for control of medically refractory epilepsy was introduced by Zabara (U.S. Pat. No. 5,540,734), and has recently received approval for use in selected patients by the Food and Drug Administration. Although helpful as a last resort in many of these patients, VNS has been shown to be limited in efficacy, with accompanying undesirable side effects, as mentioned above. VNS is also limited to the left side, since right-sided stimulation is associated with significant cardiac side effects. Patients who are candidates for VNS usually have failed all medical and other available surgical techniques. A patient presently failing VNS often has no other good treatment option available.
One proposed alternative method for treating epilepsy involves electrode stimulation of the carotid sinus nerve. For example, Patwardhan et al. (2002) Pediatric Neurosurgery 36:236-243 and U.S. Patent Publication No. 2002/0103516 A1 describe such a method. Several problems with direct, electrical carotid sinus nerve stimulation have been reported in the medical literature, however. These include the invasiveness of the surgical procedure to implant the nerve electrodes, as well as postoperative pain in the jaw, throat, face and head during stimulation. Additionally, it has been noted that direct application of high voltages sometimes required for nerve stimulation may damage the carotid sinus nerves.
Thus, it would be desirable to provide improved devices and methods for treating, reducing and/or controlling epileptic seizures. Ideally, such devices and methods would be minimally invasive and would enhance the treatment or control of epileptic seizures efficaciously, with few if any significant side effects. At least some of these objectives will be met by the present invention.
2. Description of the Background Art
Patwardhan et al. (2002) Pediatric Neurosurgery 36:236-243, and U.S. Patent Publication No. 2002/0103516 A1 describe the treatment of epilepsy by electrode stimulation of the carotid sinus nerve. U.S. Pat. Nos. 6,073,048 and 6,178,349, each having a common inventor with the present application, describe the stimulation of nerves to regulate the heart, vasculature, and other body systems. Nerve stimulation for other purposes is described in, for example, U.S. Pat. Nos. 6,292,695 B1 and 5,700,282. Publications which describe the existence of baroreceptors and/or related receptors in the venous vasculature and atria include Goldberger et al. (1999) J. Neuro. Meth. 91:109-114; Kostreva and Pontus (1993) Am. J. Physiol. 265:G15-G20; Coleridge et al. (1973) Circ. Res. 23:87-97; Mifflin and Kunze (1982) Circ. Res. 51:241-249; and Schaurte et al. (2000) J. Cardiovasc Electrophysiol. 11:64-69. The full texts and disclosures of all the references listed above are hereby incorporated fully by reference.